Selective signal system.



PATENTED JULY 17, 1906.

w. w. DEAN.

SELEGTIVE SIGNAL SYSTEM;

APPLICATION FILED JANJA. 1902.

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PATENTED JULY 17, 1906.

' W. W. DEAN.

SELECTIVE SIGNAL SYSTEM.

APPLICATION FILED J'AN.14, 1902.

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UNITED sTA n s- PATENT OFFICE.

WVILLIAM IV. DEAN, OF CHICAGO, ILLINOIS, ASSIGNOR TO WESTERN ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

SELECTIVE SIGNAL SYSTEM.

Specification of LettersPatent.

Patented July 17, 1906.

Application filed January 14,1902. Serial No. 89.658.

To all whom it may concern.-

Be it known that I, WILLIAM W. DEAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Selective Signal Systems, of which the following is a full, clear, concise, and exact description.

My invention concerns the selective operation of translating devices or other mechanism from a distant point by means of electric circuits, and has for its object more particu larly to provide improved appliances whereby the user of a telephone at a substation of a telephone system may cause the display of a predetermined one of several signals in a central office.

The broadly new feature of my invention consists in the combination, With a group of electromagnets and circuits through the agency of which one or more of the magnets maybe excited progressively in the series, of a corresponding group of interference devices actuated by the different magnets and translating devices, signals, or other mechanism controlled by the magnets, the interfering devices being arranged to be operative in a reverse order to the magnets, each to prevent the control of the magnets lower in the series over their respective translating devices or mechanismthat is to say, I may provide, say, three electromagnets in a circuit with means for operating the first one or the first two or all of the magnets progressively in the series, together with a translating device or mechanism, as a signal-lamp, which each of these magnets is adapted to control. I combine with each of these magnets an interference device operative upon the members lower in the series to prevent the control of the signals lower in the series, interfering mechanism of the second magnet being adapted to prevent the control of the signal of the magnet in the series first to be operated and that of the third or last magnet to be operated being adapted to prevent the control of the signals of the first and second magnets when the magnets are excited.

In an especially simple form of the invention which I have designed the translating mechanism is for the purpose of obtaining a selective signal, a small incandescent lamp. The interfering device is combined with the means for lighting this lamp to give a signal and consists in a circuit which traverses serially the armature-levers and resting-stops thereof of the different relays, the signallamp associated with eachrelay being located in a bridge or branch from the serial circuit at the same relay, the armature of the relay last to be operated in the series being the first in the serial local interfering-circuit, and vice versa. Thus to give one signal the first relay in the series may be excited, whereby it will be caused to close the local branch circuit through its lamp, and inasmuch as the remaining, armatures are unattracted by their relays the lamp will be lighted, or to give another s'ignal the first andsecond relays may be excited, whereupon both will close the branches through their lamps; but the second 'relay will break the circuit to the lamp branch of the first relay play of the signal there.

The relays, to repeat the language before used, are adapted for operation successively or progressively in one series, and the interfering devices are adapted to be made operaand prevent the distive successively in the reverse order in the series, so that the control from the translating device or mechanism is effective only at thatone of the relays or magnets which is highest of those operated in'the series.

As before stated, the invention is designed particularly for use in exchanges where calls received at an annunciator or distributingboard must be trunked to other switchboards for junction with the line to the station called forfor example, for the so-called Y operator or call-distributing system described in Patent No. 559,366, to 'J. P. Davis. In such a system it is desirable that the call-distributing operator shall be freed from the necessity of oral communication with the calling subscribers, the incoming lines being provided with signals to designate the different offices to which connections are to be trunked, these signals being adapted for selective operation from the substations of the lines. In adapting my invention for use in such a system I connect with each line-circuit, preferably of two conductors, several relayssay foureach of which controls selectively a signal-lamp associated with the answering-jack of the same line in the switchboard, and I furnish at the substation as many keys or switches in combination with suitable sources of current eitherat the substation or at the modifications, which also constitute features of the invention. For example, the momentary pressure of a calling-key must set and maintain the display of the corresponding signal-lamp until the call so indicated attains response. For this purpose I associate with the same local circuit a locking-winding on each of the relays controlled by its relay, the locking-winding being preferably a branch of the local circuit containing the corresponding lamp, so that simultaneously with the selective display of a lamp the relay controlling the lamp becomes self-exciting and maintains the continued display after the callingkey has been released. It is necessary also to provide means for interrupting the selfexciting condition of the relays when connection is made with the line in response to av call, and to this end I provide a cut-off relay which may control the local circuits of the calling-lamps and locking-windings in addition to its usual functions of severing the normal ground or battery connections of the line controlling the use of the line for conversation.

Further features of the invention consist in details of a circuit by means of which one or several of the relays belonging to a line may be excited without exciting other members of the group.

These several features may be more readily and fully set forth in the accompanying drawings, wherein- Figure 1 is a diagram illustrating the application of my invention to a telephoneexchange having a number of switchboards, trunking facilities being provided between the different boards, whereby a subscriber whose line terminates at one board may obtain connection with a subscribers line terminating at another board by means of telephone trunklines extending from one board to another and Fig. 2 is a diagram illustrating in detail the circuits of a telephoneline extending from a substation to a central office, the line being provided with four signals at the central office adapted to be selectively operated by means of keys at the substation.

Similar characters of reference are used to designate the same parts in both views.

Referring to Fig. 1, five switchboards A B O D E are illustrated, comprising a group connected by trunk-lines. Two subscribers lines are illustrated, one line extending from a substation F and terminating at switchboard A and another line from substation G, terminating at switchboard B. Trunk-1ines Z) c d e are illustrated, extending from switchboard A to switchboards B, C, D, and E, respectively, whereby the telephone-line from substation F, terminating at board A, may be extended to either of the other boards for connection with other lines terminating at such other boards. The trunk-line b terminates in a spring-jack at board A and in a terminal connecting-plug at switchboard B. Four signal-lamps b c d 6, corresponding to switchboards B C D E, are provided at the switchboard A, either one of which lamps may be selectively excited from the substation F to indicate to the operator which of the switchboards contains the spring-jack terminal of the line of the subscriber wanted.

.Thus if subscriber F wishes to communicate with a subscriber whose line terminates upon one of the switchboards B, C, D, or E he depresses the key which will cause the illumination of the lamp at switchboard A corresponding thereto. Assuming that subscriber F desires to communicate with subscriber G, he presses the key which will cause the lamp 1) to be lighted. It is not necessary, therefore, that the operator at board A should communicate with subscriber F. She knows from the illumination of lamp b that a subscriber whose line terminates at board B is wanted and makes connection between the springjack of the line of subscriber F and a springjack of the trunk-line Z), leading to boardB, by means of an ordinary pair of connectingplugs. Suitable signal apparatus may be provided, such as is well known in the art and need not be described, whereby the operator at board B may be informed of the call and may communicate with the subscriber F and learn the number'of the subscriber wanted. Upon receiving this information the operator at board B inserts the terminal plug of the trunk-line 1)- into the spring-jack of the called line, thus completin 'the connection desired.

Referring now to ig. 2, I will explain the apparatus and circuits which I have devised by which the four lamps b c d e at the board A may selectively be operated by depressing corresponding keys at the substation. The usual telephone and signaling apparatus is provided at the substation F, and in additionthere are four keys 6 c d 6 correspond ing, respectively, to the four lamps b c d e, which are located at the central-ofiice switchboard A. The telephone-line extends in two limbs 1 2 from the substation to the central oflice, and each of the keys at the substation is adapted when depressed to make a simple change in the circuit connections of the limbs of the telephoneline. Thus the key 6 when depressed connects the two limbs 1 2 together. The key grounds both sides of the line; the line to ground, and the key 6 grounds the limb 2 of the line. At the central ofiice a spring-jack f is provided, whereby connection may be made with the telephoneline by means of a connecting-plug in the usual manher. The limbs 1 2 of the telephone-line are connected with the line-signal apparatus by way of the armatures g g helix of the cut-off relay is included in a grounded conductor from the third contact" or test-ring of the spring-jack f, whereby said relay is excited and removes or cuts off the line signal apparatus from the telephoneline when the spring-jack f is plugged into. This cut-off relay is well known in the art,

and the circuits for operating the same need not be particularly described. An extra armature-lever g is, however, provided for this relay, said armature-lever being grounded and normally resting against the back contact g*, from which a conductor 3 is led, one terminal of each of the lamps b c d 6 being connected with this conductor. The circuit of conductor 3 includes the winding of a secondary cut-off relay 1, the function of which will hereinafter be described. Four relays b 0 d e are provided for controlling the lamps b c d e, respectively. The armatures and normal resting-contacts of these relays are connected in series one after another, and the armature b of the relay 6 which is the first of the series, is connected by a conductor 4 with the grounded centralized battery The lamps b c d 6, respectively, are included in branch conductors from the front contacts of their controlling-relays, these branch conductors also including auxiliary or locking windings of the relays, so that when said relays are once excited they will be maintained in an excited condition by the current which fiows through thelamps until the circuit is broken by the armature g? ofthe cut-01f relay. Since the armatures of the relays are serially connected through their back contacts, it is evident that when any one of the armatures is attracted it will break the circuit which supplies battery to all the armatures farther on in the series, so that none of the lamps connected below that point can receive current. Thus when the armature b, which is the first in the series, is attracted it closes circuit of grounded battery it through the lamp 6 and the retainingwinding of the relay to ground by way of conductor 3 and the armature g and back contact 9 of the cut-off relay; but the armatures of all the rest of the relays are cut off from battery, so that whether such armatures are attracted or not the remaining lamps will not be lighted. In this way each of the relay-armatures when attracted cuts Y off all the armatures farther on in the series. and e are of the ordinary type,

The relays d The key (Z connects the limb 1 of,

and their normal. resting-contacts of the cut-ofi relay '9. The.

except that they are provided with a retaining-winding, as heretofore explained. The relay 6 is a polarized relay and is wound and connected in circuit in such a manner as to attract its armature only when receiving current of positive sign from the battery h that is to say, only when the current flows in the direction of the arrow illustrated in association therewith. The relay 0 is peculiarly constructed, being of the kind known as a consequent-pole relay. This relay has a rectangular core forming a closed magnetic circuit. In order that a field of force may be produced which will cause the armature 0* to be drawn over, it is necessary that the two sides of the core be magnetized in such a way as to produce consequent poles, a north pole being jointly produced by the two windings at one end of the rectangular core and a south pole being similarly produced at the other end. If the current circulates only in a winding on one side of the core or if it circulates in the windings on both sides of the core,.but in such a way that the magnetic field of force set up by one winding will assist the magnetic field set up by the other, the armature a will not be attracted, since the core of the relay in such a case constitutes a complete magnetic circuit for the field of force; but if of the rectangular core receive current flowing in such directions that the magnetic fields set up on each side of the core will oppose one another the north pole produced at the end of the core by the winding on one side will be met by a similar north pole produced by the winding on the other side. The lines of force will no longer find a complete circuit within the core and will be forced outward, whereby the armature a will be attracted. The centralized battery 7b is divided into two parts h 77/2, and the conductor 4, leading to the armatures of the relays, is tapped onto the battery between said parts h if. The positive pole of the battery is grounded, and the negative pole is connected with the back contact of the armature g and so with the limb 2 of the telephone-line by a conductor 5, which includes the winding 6 of relay 6 and the winding 0 of relay 0 A conductor 6 connects the limb 1 of the telephone-line through the armature g and its back contact of the cut-off relay 9 and armature i and its back contact of the secondar cut-off relay 2' with the middle point of the battery h, where the conductor 4 is tapped on, said conductor 6 including the windings b", 0, and d of relays b 0 and (Z respectively. The two armatures t i of the secondary cut-off relay i normally maintain the continuity of conductors 5 6; but when this relay is excited the circuit of each of said conductors is broken by'the drawing up of said armatures, thus disconnecting both poles of the battery h from line. The winding 0 of the windings on opposite sides rent is broken at the back contact of armathe other, and the lines of force find a complete circuit in the rectangular core of the relay; but if both limbs of the telephone-line be simultaneously grounded. the current will not circulate in the manner just described, but will flow in parallel over the limbs 1 2 of the telephone-line through the portions it its, re'

spectively, of the battery, the flow of current through the windings c c of the relay c be ing in a direction to set up opposing magnetic fields, whereby consequent poles are produced at the ends of the rectangular core, causing the armature c to be attracted.

The operation of the system is as follows: The subscriber at substation F before taking his telephone for use ascertains by consulting his telephone directory what switchboard of the group contains the spring-jack terminal of the subscribers line with which he desires to be connected. He then depresses that one of his buttons 5 c d e which corresponds with the switchboard in question, whereby the corresponding lamp at switchboard A may be illuminated to attract the attention of the operator and inform her to what board she will be expected to trunk the call. If key N is depressed, it connects the two limbs of the telephone-line together, whereby a complete circuit is established for the portion lb of the battery 7%, said circuit including armature t of secondary cut-oll' relay 'i, conductor 6, winding d of relay d winding 0 of relay 0, winding?) of relay b limb 1 of the telephone-line, through the contacts of the key N, to the other limb 2 of the telephone line, thence to conductor 5, winding 0 of relay c, and winding 6 of relay c armature t" of relay t, to the negative pole of the battery.

Current in the circuit thus formed circulates in a direction to which relay b is responsive, so that the armature b is drawn up and closes the branch circuit 4 3, which includes the retaining-winding of the relay and the signallamp I), the lamp being lighted. Both relays d and e are excited and draw up their arma tures; but the lamps (Z c are not lighted, because the circuit by which said lamps are supplied with current is broken by the drawing up of armature D The consequent-pole relay 0 is not excited, because the magnetic field set up by the windings c 0 do not oppose one another; but even if this relay were excited the lamp 0 would not be lighted, because the circuit by which said amp is supplied with curture b The lamp 1) then alone is lighted by the depression of key I). When key 0 is de pressed, both limbs 1 2 of the telephone-line are connected together to ground. A circuit is now completed from the portion h of hat tery 71 through the earth to the substation, thence through the contacts of key 0 and over limbs 1 2 of the line in parallel to the negative pole of the battery h, this circuit in cluding the windings c c of relay 0 The current inv this circuit is also reinforced by current from the portion kg of the battery which. flows through battery it, whose resistance is practically negligible, to earth, and thence to the substation through the contacts of key 0 and over limb 2 of the line to the neg ative pole of the battery. It will be noted that practically no current will flow from battery h over the limb 6 to the substation, as a path of comparatively no resistance is offered for the same through the battery it and earth. This circuit includes the windings of all the relays; but the relay 1) is not excited, because the current is flowing in an opposite direction from that required to operate the same. The

current flowing in the windings c c is of proper direction to set up opposing magnetic fields in the two halves of the rectangular core, whereby consequent poles are produced at the ends of the core and the armature c is attracted, closing the branch circuit, which includes the retaining-windings of the relay 0 and the signal-lamp c, said lamp being lighted. The relays d and e are both excited but the lamps cl and e do not receive current, because their circuit is broken by the armature c. When key (1 is depressed, grounding the limb 1 of the telephone-line, circuit is completed from ground through the portion h of the battery, through conductor 6, including windings d c I), to limb 1 of the telephone-line, and to ground. The relay (i is thus excited and attracts its armature, closing the local circuit, which includes the'retaining-winding and the lamp (1, whereby said lamp is lighted. The flow of current in the circuit is in the wrong direction for relay 12 to respond, and only one winding of relay 0 receives current. Relay 6 is not included in the circuit. The lamp d, therefore, alone is lighted. When key (2 is depressed, circuit is completed from ground at the central o'f'lice, through the two portions h 71 of the battery, winding 6 of relay 6 conductor 5, Winding 0" of relay a, limb 2 of the telephone-line, to ground. This circuit only includes windings of two of the relays, and of these two the relay 0 is irresponsive, because only one of its windings receives current. The relay 6 is attracted and draws up its armature, closing the branch circuit which includ es the lamp 0, whereby said lamp is lighted. When either one of the relays b c d c is excited, the drawing up of its armature closes the branch circuit through the corresponding signal-lamp, as before explained, and the closrod ing of any one of said branch circuits affords a path for current through the secondary cutoff relay The relay i when excited breaks the circuit of conductors 5 6, thus preventing any of said relays from receiving current over said conductors. Each relay, however, in drawing up its armature closes a local circuit through its locking-winding, so that that relay is maintained in an excited condition until the circuit is broken when the line is plugged into. As. soon as any one of the keys at the substation has been depressed, therefore, the lamp corresponding to such key is lighted and the blocking-relay or secondary cut-01f relay'i at the central office is brought into action to render the central-office signaling apparatus irresponsive to any further manipulation of the keysthat is, as soon as any one of the substation-keys has been depressed both limbs of the telephone-lineare instantly cut off from battery to prevent the sending of false signals. Since the relay 5 is responsive when the limbs of the telephoneline are connected together by the key. at the substation, it is obvious that if the line were maintained connected with the battery the closing of the telephone-bridge when the subscribers receiver is removed from its hook would have a similar effect. The provision of the secondary cut-off relay'iovercomes this objection andprevents the transmission of a false signal.

I have illustrated the usual pair of connecting-plugs and their cord-circuit for making connection with the spring-jack of telephonelines. When the operator receives a call, she notices which one of the lamps b a (Z e has been lighted, and she knows from this to what board the call must be trunked. She thereupon inserts one plug'of the pair into the spring-jack of the calling line, whereupon the cut-off relay is operated in a manner well understood and removes the line-signal apparatus from circuit, so that the lamp is extinguished. She then inserts the other plug of the pair into the spring-jack of the trunk-line leading to the board indicated by the lamp which the subscriber has lighted, and the operator at the distant board then communicates with the calling subscriber and completesthe desired connection.

Having thus described my invention, I claim as new, and desire to secure by Letters Patent, the following:

-1. The combination with a source of current, of a number of responsive devices and branch circuits including the same, a number of relay-magnets and armature-switches operated thereby for controlling said branch circuits, a circuit including said source of current with said armature-switches in series, each armature-switch being adapted when actuated to cut off all the remaining armature-switches farther on in the series, and circuits independent of said armature-switches for exciting the different relay-magnets, substantially as set forth.

2, The combination with a telephone-line circuit extending from a substation to a central office, of a number of signal-indicators associated with the line at the central office, branch circuits including said signal-indicators, relays included in the line-circuit, a source of current at the central oiiice, switches at the substation of the line for determining the flow of current through said relays, and armature-switches, operated by said relays, controlling said branch circuits, said armature-switches being serially connected in a circuit which includes a source of current, whereby each relay armature-switch, when operated to close circuit through its branch circuit and signal-indicator, cuts off the connection of all the armature-switches farther on in the series, as set forth.

3 The combination with a line-circuit having two limbs 1 2, of a source of current 7L2 and conductors 5 6 connecting the poles of said source of current with the limbs 1 2, respectively, a consequent-pole electromagnet having windings c 0 included in conductors 5 6, respectively, a switch 6 for connecting the two limbs of the line-circuit together, whereby a circuit including the two windings c c serially with the source of current 7L2 may 95 be established, a second source of current 7i connected between one pole of the first-mentioned source of current and ground, a switch 0 for grounding both limbs of the line-circuit, whereby a circuit may be established :00 from said source of current h including the two windings c c in multiple and mechanism controlled by said magnet, substantially as described.

4. The combination with a line-circuit hav- 105 ing two limbs 1 2, of a source of current 7L2 and conductors 5 6 connecting the poles of said source of current with the limbs 1 2, respectively, a consequent-pole electromagnet 0 having windings c 0 included in conducno tors 5 6, respectively, a polarized electromagnet 6 included in the circuit of conductor 6,

a second source of current h connected between conductor 6 and ground, a switch 19 adapted to connect the two limbs ofthe line- I I 5 circuit together, aswitch 0 adapted to ground both limbs of the line-circuit and signal devices controlled by said magnets, substantially as set forth.

5. In a signaling-circuit divided in multi- I ple branches containing a source of current and having switches for controlling the current through each of said branches, of a relay for each branch having a winding therein, a consequent-pole relay having a winding in 12 5 each of said branches, a translating device for each relay in a circuit controlled thereby, and an interfering-circuit controlled by said consequent-pole relay adapted when said relay is excited to prevent the control of said 13 other relays over their respective translating devices, as described.

6. In combination in a signaling-circuit a neutral relay and a polarized relay, and means for applying current of either direction in the circuit to operate the neutral relay or both relays, a translating device controlled by each relay and an interferingcir cuit controlled by said polarized relay and adapted to prevent the control of said neutral relay over its said translating device, whereby the translating devices may be selectively operated.

7. In combination a series of magnets and means for exciting one or more'of said magnets, of a translating device controlled by each of the magnets and an interfering mechanism also controlled by each magnet, each said interfering mechanism being adapted to prevent the control of the magnets over their respective translating devices in a reverse serial arrangement; whereby any translating device may be independently excited, as described.

8. The combination with a group of relays and circuits, a source of current for exciting different members of the relays consecutively in a series, of a translating device for each of said relays in an electric circuit controlled thereby, and interfering circuit connections controlled by each of said relays in a reverse serial arrangement, each relay being thereby adapted to prevent the control of the other relays of the series excited at the same time with it over their respective translating devices, as described.

9. In combination with a group of relays, circuits and switches for momentarily exciting different numbers of the relays consecutively in a series, mechanism controlled by each relay, a locking circuit of each relay closed by the relay, and interfering circuit connections of each relay actuated thereby, such interfering connections of each relay being adapted to renderineffective the control of the other relays over their individual mechanism in serial order reverse to that of the operation of said relays, substantially as described.

10. In combination, a signaling-circuit, of two line conductors and a return conductor therefor, a relay in each of the line conductors, a signal controlled by each of said relays and a relay inboth of said line conductors adapted for operation by current in both said line conductors and the return conductor, and means for applying current in the line to operate either of said first-mentioned relays or all of the relays, a signal in the circuit made operative by said relay in both line conductors, said circuit being adapted to prevent the control of said other relays over their respective signals, as described.

11. In combination with a telephone-line, several relays at the central oflice thereof and means for operating them, a signal controlled by each relay and a locking-circuit also controlled by the relay adapted to maintain the display of the signal, means actuated in the operation of each signal adapted to prevent the operation of the other signals by their relays, a key for each relay at the substation adapted to momentarily excite the corre:

sponding relay, said locking-circuits being formed in part of a common conductor, means for making connection with the line, and a switch operated in making such connection adapted to break said common conductor of the locking-circuits, as described.

12. The combination with a line-circuit, of a source of current connected therewith, a relay in the circuit and a switch for controlling the flow of current in the circuit, a local circuit controlled by said. relay and a responsive device and a cut-off relay included in said 10- cal circuit, said cut-off relay controlling the main circuit, substantially as set forth.

13. The combination with a telephone-line extending from a substation to a central office, of a source of current and a relay connected with the line at the central O'fIlCG, a switch at the substation for controlling the flow of current in the line, a local circuit adapted to be closed by said relay when excited, a locking-winding for said relay, a responsive device, and a cut-off relay, all included in said local circuit, said cut-off relay being adapted when excited to interrupt the main circuit, substantially as set forth.

In witness whereof I hereunto subscribe my name this 17th day of August, A. D.

WILLIAM W. DEAN. Witnesses:

ELLA EDLER, ADELL HooKE'rT. 

